The main advantages of tanks of the aforementioned type are lightness and a sufficient resistance for withstanding the pressures exerted by fluids contained in the tank or bottle.
Conveying compressed gas or liquids under pressure, such as, for example, liquefied butane or propane, in pressure-resisting tight tanks or bottles, is well-known, with the tanks or bottles most often being made of steel such that the weight of the tank or bottle is at least equal to the weight of the contained fluid. Thus, the handling of the empty tanks or bottles is nearly as difficult as the handling of the full tanks or bottles, and that the transportation expenses for the empty tanks or bottles are substantially the same an the expenses incurred in transporting the full tanks or bottles.
The technical problem posed here is not evident because the features of lightness and pressure resistance are often incompatible.
Light tanks or bottles incapable of withstanding relatively high pressures and tanks or bottles requiring the use of very costly material have been proposed in the prior art.
To enable the general public to have access to tanks or bottles of the aforementioned type, materials of reasonable cost are used and, for example, unidirectional composites with a thermoplastic matrix are employed for manufacturing the tanks or bottles. The tank or bottle always comprises an inner sheath made of a metallic material, with the rain function of the sheath being to provide a tight or sealed inner liner. As a result of such manufacturing techniques, the thickness of the tank or bottle increases thereby contributing to the total weight.
In, for example, U.S. Pat. No. 4,589,562, a tank is proposed for withstanding high pressures by providing a composite winding around a cylindrical body portion thereof and over a portion of the respective opposed end portion. However, since the composite winding does not cover the entire end portions, the end portions are not sufficiently reinforced. Thus, it is not possible to decrease the thickness of the tank and enable a reduction in the weight thereof.